Complications Analysis of Polytetrafluoroethylene Grafts Used for Middle Hepatic Vein Reconstruction in Living-Donor Liver Transplantation T.-Y. Ha, S. Hwang, D.-H. Jung, C.-S. Ahn, K.-H. Kim, D.-B. Moon, G.-W. Song, G.-C. Park, H.-W. Park, Y.-H. Park, B.-H. Jung, S.-H. Kang, and S.-G. Lee ABSTRACT Background. We previously showed that ringed polytetrafluoroethylene (PTFE) grafts combined with small allograft patches showed high patency rates similar to those of iliac vein grafts and therefore that they can be used for middle hepatic vein (MHV) reconstruction. Although such use of PTFE graft showed high patency rates, its long-term safety regarding infection and other types of complications were not presented. In this study, we investigated the actual risk of complications directly associated with PTFE graft interposition for MHV reconstruction. Methods. During the study period of 30 months, we performed 215 cases of adult livingdonor liver transplantation with modified right lobe graft and PTFE grafts. We classified the potential complications directly associated with PTFE graft interposition as infectious and surgical complications. The medical records of study patients were retrospectively reviewed. Results. MHV graft patency rate was 76.3% at 6 months and 36.7% at 12 months. Their 1-year graft and patient survival rates were 92.6% and 93.5%, respectively. The 1-year actual incidences of infectious complication and surgical complication were near zero and 1 case (0.5%), respectively. In 1 recipient, the PTFE graft penetrated into the stomach wall 6 months after transplantation, but the patient did not complain of any specific symptoms. The PTFE graft was removed with the use of laparotomy, and the patient recovered uneventfully. Conclusions. Although the incidence of PTFE grafteassociated complication rate is very low, we suggest that it is necessary to closely monitor the PTFE graft, because unexpected complications can happen during long-term follow-up.
M
IDDLE HEPATIC VEIN (MHV) reconstruction with an interposition vessel graft has been established as a standard procedure for living-donor liver transplantation (LDLT) using a right lobe graft when the donor’s MHV trunk is preserved in the donor’s remnant liver. Large-size vein allografts are suitable for MHV reconstruction, but their supply is often limited. Because of easy availability of synthetic grafts, polytetrafluoroethylene (PTFE) grafts have been used instead of sizable vessel allografts [1e3]. We have previously shown that acceptably high patency rates were achieved after technical refinement with the use of ringed PTFE grafts combined with small vessel patches [1]. Although such use of PTFE graft showed ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 46, 845e849 (2014)
high patency rates, its long-term safety regarding infection and other types of complications has not been studied yet. In this study, we investigated the actual risk of complications directly associated with PTFE graft interposition for MHV reconstruction during LDLT. From the Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. Address reprint requests to Shin Hwang, MD, PhD, Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Poongnap-dong, Songpa-gu, 138-736, Korea. E-mail: [email protected] 0041-1345/14/$esee front matter http://dx.doi.org/10.1016/j.transproceed.2013.10.054 845
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HA, HWANG, JUNG ET AL
Table 1. Clinical Profiles of the 215 Patients Who Underwent Living-Donor Liver Transplantation Using a Modified Right Lobe Graft With Polytetrafluoroethylene Graft Interposition Parameter
Value
Recipient age (y) Recipient sex: male/female (n/n) Primary diagnosis (n) Hepatitis B viruseassociated liver cirrhosis Hepatitis C viruseassociated liver cirrhosis Alcoholic liver disease Acute liver failure Other Concurrent hepatocellular carcinoma (n) MELD score Donor age (y) Donor sex: male/female (n/n) ABO blood group incompatibility (n) GRWR 6-month MHV graft patency rate 1-year MHV graft patency rate 1-year liver graft survival rate 1-year patient survival rate
52.8 4.9 145/70 139 18 32 15 11 116 (51.6%) 17.1 8.7 27.3 7.3 165/50 34 (15.8%) 1.07 0.3 76.3% 36.7% 92.6% 93.5%
Abbreviations: MELD, Model for End-Stage Liver Disease; GRWR, graftrecipient weight ratio; MHV, middle hepatic vein.
PATIENTS AND METHODS During a study period of 30 months from March 2010 to August 2012, we performed 215 cases of adult LDLT with the use of a modified right lobe graft and PTFE grafts [1,4]. The clinical profiles are summarized in Table 1. During the LDLT operation, we used ringed PTFE grafts (GoreTex) of an internal diameter of 10 mm. After we inserted a niche to enlarge the orifices of hepatic vein branch segments 5 and 8, we applied an intervening allograft patch for end-to-side anastomosis
Fig 1. Computerized tomographic (CT) follow-up before PTFE graft migration. Native cirrhotic liver (A) was removed and a right liver graft implanted. Followup CT images showed patent PTFE graft of middle hepatic vein reconstruction at post-transplantation 1 week (B and C) and 3 months (D).
of MHV branches. After graft implantation, we diffusely sprayed fibrin glue over the PTFE graft with expectation of infection protection through sealing the microporous structure of the grafts against potential infection risks such as bile leaks. Detailed surgical technique was described previously [1]. The LDLT recipients were closely monitored according to institutional follow-up guidelines. During the 1st year after discharge from initial hospitalization, abdomen computerized tomography was performed with 2e4-month intervals to detect subclinical complications and hepatocellular carcinoma recurrence [5,6]. In the present study, we classified the potential complications directly associated with PTFE graft interposition as infectious or surgical complications. Infectious complications included abscess formation around PTFE graft, requiring percutaneous drainage or PTFE graft removal. Surgical complications included bleeding and PTFE graft migration requiring any type of intervention. The medical records of study patients were retrospectively reviewed in August 2013; thus the minimal follow-up period was set to be 1 year. The present study protocol was approved by the Institutional Review Board of our institution.
RESULTS Survival Outcome and MHV Patency
In this study cohort of 215 patients, the MHV graft patency rate was 76.3% at 6 months and 36.7% at 12 months. The 1-year liver graft survival rate was 92.6%, and 2 of 3 patients who underwent retransplantation survived, making the 1-year patient survival rate 93.5% (Table 1). Incidence of PTFE GrafteAssociated Complications
Fluid collection and hematoma around the graft liver surface was occasionally detected, but no patient required
PTFE GRAFT COMPLICATIONS
847
Fig 2. Computerized tomographic follow-up during PTFE graft migration 6 months after transplantation. Air bubbles were shown within the PTFE graft (A) with partial penetration into the gastric wall (B).
percutaneous drainage or exploratory laparotomy for evacuation of abscess. Partial or complete thrombus was observed in most PTFE grafts, but there was no evidence implicating luminal infection, such as air bubble formation or unusual liquefaction of luminal thrombus. Thus the actual incidence of infectious complication was nearly absent during 1st year. There was no episode of bleeding directly related to PTFE graft per se. The PTFE graft remained in position through the 1st year in all recipients except one, in whom it migrated toward the stomach. The clinical course of this case is described below in detail. Thus, the actual incidence of surgical complication was 1 out of 215 cases (0.5%) during the 1st year. Case Presentation of Accidental Migration of PTFE Graft Into the Stomach
This patient was a 48-year-old man with hepatitis B viruseassociated liver cirrhosis and Model for End-Stage Liver Disease score of 16. The patient recovered uneventfully after LDLT operation with a modified right lobe graft and discharged 2 weeks after LDLT (Fig. 1). On computerized tomographic follow-up at 6 months, abnormal air shadow was identified within the PTFE graft (Fig. 2). Meticulous review of the imaging studies revealed that the PTFE graft was partially buried into the stomach wall, implicating unusual migration and penetration into the stomach. The PTFE graft was occluded with partial filling of luminal air. At this time, the patient complained
Fig 3. Further migration of PTFE graft 7 months after transplantation. (A) The PTFE graft was more deeply buried into the stomach on computerized tomographic images. (B) Gastrofibroscopy showed complete penetration of the PTFE graft into the gastric lumen.
of no specific symptoms. Gastrofibroscopic examination revealed the PTFE graft was freely exposed into the gastric lumen (Fig. 3). Exploratory laparotomy was performed 7 months after transplantation, and the PTFE graft was removed (Fig. 4). The perforated gastric wall was primarily repaired. The patient recovered uneventfully and at the time of writing had lived well for 12 months after reexploration. DISCUSSION
Clinical application of PTFE graft for MHV reconstruction has had a great impact on selection of right liver grafts for LDLT. Previously, vessel conduit allograft for MHV reconstruction was not sufficiently available in many countries where deceased-donor organ recovery or tissue donation was not active. Presently, it is accepted that PTFE or other synthetic grafts can be a useful substitute for vessel allograft. Thus, the rationale to use an extended right liver graft has been weakened, and the modified right liver graft regarded to be the standard type of right liver graft [1,7e9]. The patency of PTFE graft for MHV reconstruction was assessed in a few studies [1,2], but information on synthetic vessel grafteassociated complications were not available yet in the literature. Therefore, to our knowledge, this is the first report focused on the safety of synthetic vessel grafts. As expected, the actual 1-year incidence of PTFE grafteassociated complication was only 1 case out of 215
848
HA, HWANG, JUNG ET AL
Fig 4. Intraoperative and postoperative findings. After dissection of the gastric wall, (A) the PTFE graft was partially exposed and (B) further dissection led to exposure of its full length. (C) The liver grafteside PTFE graft was transected first and then (D) removed from the recipient inferior vena cava, thus showing (E) a large defect at the gastric wall. Computerized tomographic image taken at 8 months after transplantation showed uneventful recovery (F).
patients. This acceptably low incidence appears to be very promising for using synthetic graft more widely. However, the features of this complication case were unexpectedly unusual. If the PTFE graft is not occluded with luminal thrombus formation, such a condition carries high risk of air embolism and septicemia, which can lead to a grave clinical sequence. If smaller-size PTFE graft without outer rings had been used, such gastric penetration might not happen, because the material is not rigid. Because outer rings have the merit of prolonged patency, we think that there is no reason to prefer plain PTFE graft to ringed material [1]. We have seldom used polyethylene terephthalate (Dacron) graft for vascular reconstruction during surgery of hepatobiliary malignancy, in which the wall porosity is much larger than that of expanded PTFE graft. Dacron graft can be used in renal vein reconstruction because of its flexibility [10], but its porosity can increase the risk of infection when it is used in a potentially contaminated environment, such as with bile leak after LDLT [11,12]. Therefore, the results of the present study are valid only for expanded PTFE vessel grafts.
In conclusion, although the incidence of PTFE grafte associated complications is very low, we suggest that it is necessary to closely monitor the PTFE graft, because unexpected complications can occur during long-term follow-up.
REFERENCES [1] Hwang S, Jung DH, Ha TY, et al. Usability of ringed polytetrafluoroethylene grafts for middle hepatic vein reconstruction during living donor liver transplantation. Liver Transpl 2012;18: 955. [2] Yi NJ, Suh KS, Lee HW, et al. An artificial vascular graft is a useful interpositional material for drainage of the right anterior section in living donor liver transplantation. Liver Transpl 2007;13: 1159. [3] Pomposelli JJ, Akoad M, Khwaja K, et al. Evolution of anterior segment reconstruction after live donor adult liver transplantation: a single-center experience. Clin Transplant 2012; 26:470. [4] Moon DB, Lee SG, Hwang S, et al. More than 300 consecutive living donor liver transplants a year at a single center. Transplant Proc 2013;45:1942.
PTFE GRAFT COMPLICATIONS [5] Hwang S, Ahn CS, Kim KH, et al. Super-selection of a subgroup of hepatocellular carcinoma patients at minimal risk of recurrence for liver transplantation. J Gastrointest Surg 2011;15:971. [6] Hwang S, Moon DB, Ahn CS, et al. Risk-based long-term screening for hepatocellular carcinoma recurrence after livingdonor liver transplantation. Transplant Proc; 2013. In press. [7] Sugawara Y, Makuuchi M. Advances in adult living donor liver transplantation: a review based on reports from the 10th anniversary of the adult-to-adult living donor liver transplantation meeting in Tokyo. Liver Transpl 2004;10:715. [8] Sano K, Makuuchi M, Miki K, et al. Evaluation of hepatic venous congestion: proposed indication criteria for hepatic vein reconstruction. Ann Surg 2002;236:241.
849 [9] Asakuma M, Fujimoto Y, Bourquain H, et al. Graft selection algorithm based on congestion volume for adult living donor liver transplantation. Am J Transplant 2007;7:1788. [10] Tinay I, Temiz Y, Ilker Y, et al. An alternative for short renal vein during kidney transplantation: long-term experience with polyethylene terephthalate (Dacron) vascular graft. Urology 2013;82:245. [11] Altarabsheh SE, Deo SV, Berbari E, et al. Prosthetic graft infection, five years after ascending aortic replacement. J Card Surg 2012;27:220. [12] Bisdas T, Beckmann E, Marsch G, et al. Prevention of vascular graft infections with antibiotic graft impregnation prior to implantation: in vitro comparison between daptomycin, rifampin and nebacetin. Eur J Vasc Endovasc Surg 2012;43:448.
M
IDDLE HEPATIC VEIN (MHV) reconstruction with an interposition vessel graft has been established as a standard procedure for living-donor liver transplantation (LDLT) using a right lobe graft when the donor’s MHV trunk is preserved in the donor’s remnant liver. Large-size vein allografts are suitable for MHV reconstruction, but their supply is often limited. Because of easy availability of synthetic grafts, polytetrafluoroethylene (PTFE) grafts have been used instead of sizable vessel allografts [1e3]. We have previously shown that acceptably high patency rates were achieved after technical refinement with the use of ringed PTFE grafts combined with small vessel patches [1]. Although such use of PTFE graft showed ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 46, 845e849 (2014)
high patency rates, its long-term safety regarding infection and other types of complications has not been studied yet. In this study, we investigated the actual risk of complications directly associated with PTFE graft interposition for MHV reconstruction during LDLT. From the Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. Address reprint requests to Shin Hwang, MD, PhD, Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Poongnap-dong, Songpa-gu, 138-736, Korea. E-mail: [email protected] 0041-1345/14/$esee front matter http://dx.doi.org/10.1016/j.transproceed.2013.10.054 845
846
HA, HWANG, JUNG ET AL
Table 1. Clinical Profiles of the 215 Patients Who Underwent Living-Donor Liver Transplantation Using a Modified Right Lobe Graft With Polytetrafluoroethylene Graft Interposition Parameter
Value
Recipient age (y) Recipient sex: male/female (n/n) Primary diagnosis (n) Hepatitis B viruseassociated liver cirrhosis Hepatitis C viruseassociated liver cirrhosis Alcoholic liver disease Acute liver failure Other Concurrent hepatocellular carcinoma (n) MELD score Donor age (y) Donor sex: male/female (n/n) ABO blood group incompatibility (n) GRWR 6-month MHV graft patency rate 1-year MHV graft patency rate 1-year liver graft survival rate 1-year patient survival rate
52.8 4.9 145/70 139 18 32 15 11 116 (51.6%) 17.1 8.7 27.3 7.3 165/50 34 (15.8%) 1.07 0.3 76.3% 36.7% 92.6% 93.5%
Abbreviations: MELD, Model for End-Stage Liver Disease; GRWR, graftrecipient weight ratio; MHV, middle hepatic vein.
PATIENTS AND METHODS During a study period of 30 months from March 2010 to August 2012, we performed 215 cases of adult LDLT with the use of a modified right lobe graft and PTFE grafts [1,4]. The clinical profiles are summarized in Table 1. During the LDLT operation, we used ringed PTFE grafts (GoreTex) of an internal diameter of 10 mm. After we inserted a niche to enlarge the orifices of hepatic vein branch segments 5 and 8, we applied an intervening allograft patch for end-to-side anastomosis
Fig 1. Computerized tomographic (CT) follow-up before PTFE graft migration. Native cirrhotic liver (A) was removed and a right liver graft implanted. Followup CT images showed patent PTFE graft of middle hepatic vein reconstruction at post-transplantation 1 week (B and C) and 3 months (D).
of MHV branches. After graft implantation, we diffusely sprayed fibrin glue over the PTFE graft with expectation of infection protection through sealing the microporous structure of the grafts against potential infection risks such as bile leaks. Detailed surgical technique was described previously [1]. The LDLT recipients were closely monitored according to institutional follow-up guidelines. During the 1st year after discharge from initial hospitalization, abdomen computerized tomography was performed with 2e4-month intervals to detect subclinical complications and hepatocellular carcinoma recurrence [5,6]. In the present study, we classified the potential complications directly associated with PTFE graft interposition as infectious or surgical complications. Infectious complications included abscess formation around PTFE graft, requiring percutaneous drainage or PTFE graft removal. Surgical complications included bleeding and PTFE graft migration requiring any type of intervention. The medical records of study patients were retrospectively reviewed in August 2013; thus the minimal follow-up period was set to be 1 year. The present study protocol was approved by the Institutional Review Board of our institution.
RESULTS Survival Outcome and MHV Patency
In this study cohort of 215 patients, the MHV graft patency rate was 76.3% at 6 months and 36.7% at 12 months. The 1-year liver graft survival rate was 92.6%, and 2 of 3 patients who underwent retransplantation survived, making the 1-year patient survival rate 93.5% (Table 1). Incidence of PTFE GrafteAssociated Complications
Fluid collection and hematoma around the graft liver surface was occasionally detected, but no patient required
PTFE GRAFT COMPLICATIONS
847
Fig 2. Computerized tomographic follow-up during PTFE graft migration 6 months after transplantation. Air bubbles were shown within the PTFE graft (A) with partial penetration into the gastric wall (B).
percutaneous drainage or exploratory laparotomy for evacuation of abscess. Partial or complete thrombus was observed in most PTFE grafts, but there was no evidence implicating luminal infection, such as air bubble formation or unusual liquefaction of luminal thrombus. Thus the actual incidence of infectious complication was nearly absent during 1st year. There was no episode of bleeding directly related to PTFE graft per se. The PTFE graft remained in position through the 1st year in all recipients except one, in whom it migrated toward the stomach. The clinical course of this case is described below in detail. Thus, the actual incidence of surgical complication was 1 out of 215 cases (0.5%) during the 1st year. Case Presentation of Accidental Migration of PTFE Graft Into the Stomach
This patient was a 48-year-old man with hepatitis B viruseassociated liver cirrhosis and Model for End-Stage Liver Disease score of 16. The patient recovered uneventfully after LDLT operation with a modified right lobe graft and discharged 2 weeks after LDLT (Fig. 1). On computerized tomographic follow-up at 6 months, abnormal air shadow was identified within the PTFE graft (Fig. 2). Meticulous review of the imaging studies revealed that the PTFE graft was partially buried into the stomach wall, implicating unusual migration and penetration into the stomach. The PTFE graft was occluded with partial filling of luminal air. At this time, the patient complained
Fig 3. Further migration of PTFE graft 7 months after transplantation. (A) The PTFE graft was more deeply buried into the stomach on computerized tomographic images. (B) Gastrofibroscopy showed complete penetration of the PTFE graft into the gastric lumen.
of no specific symptoms. Gastrofibroscopic examination revealed the PTFE graft was freely exposed into the gastric lumen (Fig. 3). Exploratory laparotomy was performed 7 months after transplantation, and the PTFE graft was removed (Fig. 4). The perforated gastric wall was primarily repaired. The patient recovered uneventfully and at the time of writing had lived well for 12 months after reexploration. DISCUSSION
Clinical application of PTFE graft for MHV reconstruction has had a great impact on selection of right liver grafts for LDLT. Previously, vessel conduit allograft for MHV reconstruction was not sufficiently available in many countries where deceased-donor organ recovery or tissue donation was not active. Presently, it is accepted that PTFE or other synthetic grafts can be a useful substitute for vessel allograft. Thus, the rationale to use an extended right liver graft has been weakened, and the modified right liver graft regarded to be the standard type of right liver graft [1,7e9]. The patency of PTFE graft for MHV reconstruction was assessed in a few studies [1,2], but information on synthetic vessel grafteassociated complications were not available yet in the literature. Therefore, to our knowledge, this is the first report focused on the safety of synthetic vessel grafts. As expected, the actual 1-year incidence of PTFE grafteassociated complication was only 1 case out of 215
848
HA, HWANG, JUNG ET AL
Fig 4. Intraoperative and postoperative findings. After dissection of the gastric wall, (A) the PTFE graft was partially exposed and (B) further dissection led to exposure of its full length. (C) The liver grafteside PTFE graft was transected first and then (D) removed from the recipient inferior vena cava, thus showing (E) a large defect at the gastric wall. Computerized tomographic image taken at 8 months after transplantation showed uneventful recovery (F).
patients. This acceptably low incidence appears to be very promising for using synthetic graft more widely. However, the features of this complication case were unexpectedly unusual. If the PTFE graft is not occluded with luminal thrombus formation, such a condition carries high risk of air embolism and septicemia, which can lead to a grave clinical sequence. If smaller-size PTFE graft without outer rings had been used, such gastric penetration might not happen, because the material is not rigid. Because outer rings have the merit of prolonged patency, we think that there is no reason to prefer plain PTFE graft to ringed material [1]. We have seldom used polyethylene terephthalate (Dacron) graft for vascular reconstruction during surgery of hepatobiliary malignancy, in which the wall porosity is much larger than that of expanded PTFE graft. Dacron graft can be used in renal vein reconstruction because of its flexibility [10], but its porosity can increase the risk of infection when it is used in a potentially contaminated environment, such as with bile leak after LDLT [11,12]. Therefore, the results of the present study are valid only for expanded PTFE vessel grafts.
In conclusion, although the incidence of PTFE grafte associated complications is very low, we suggest that it is necessary to closely monitor the PTFE graft, because unexpected complications can occur during long-term follow-up.
REFERENCES [1] Hwang S, Jung DH, Ha TY, et al. Usability of ringed polytetrafluoroethylene grafts for middle hepatic vein reconstruction during living donor liver transplantation. Liver Transpl 2012;18: 955. [2] Yi NJ, Suh KS, Lee HW, et al. An artificial vascular graft is a useful interpositional material for drainage of the right anterior section in living donor liver transplantation. Liver Transpl 2007;13: 1159. [3] Pomposelli JJ, Akoad M, Khwaja K, et al. Evolution of anterior segment reconstruction after live donor adult liver transplantation: a single-center experience. Clin Transplant 2012; 26:470. [4] Moon DB, Lee SG, Hwang S, et al. More than 300 consecutive living donor liver transplants a year at a single center. Transplant Proc 2013;45:1942.
PTFE GRAFT COMPLICATIONS [5] Hwang S, Ahn CS, Kim KH, et al. Super-selection of a subgroup of hepatocellular carcinoma patients at minimal risk of recurrence for liver transplantation. J Gastrointest Surg 2011;15:971. [6] Hwang S, Moon DB, Ahn CS, et al. Risk-based long-term screening for hepatocellular carcinoma recurrence after livingdonor liver transplantation. Transplant Proc; 2013. In press. [7] Sugawara Y, Makuuchi M. Advances in adult living donor liver transplantation: a review based on reports from the 10th anniversary of the adult-to-adult living donor liver transplantation meeting in Tokyo. Liver Transpl 2004;10:715. [8] Sano K, Makuuchi M, Miki K, et al. Evaluation of hepatic venous congestion: proposed indication criteria for hepatic vein reconstruction. Ann Surg 2002;236:241.
849 [9] Asakuma M, Fujimoto Y, Bourquain H, et al. Graft selection algorithm based on congestion volume for adult living donor liver transplantation. Am J Transplant 2007;7:1788. [10] Tinay I, Temiz Y, Ilker Y, et al. An alternative for short renal vein during kidney transplantation: long-term experience with polyethylene terephthalate (Dacron) vascular graft. Urology 2013;82:245. [11] Altarabsheh SE, Deo SV, Berbari E, et al. Prosthetic graft infection, five years after ascending aortic replacement. J Card Surg 2012;27:220. [12] Bisdas T, Beckmann E, Marsch G, et al. Prevention of vascular graft infections with antibiotic graft impregnation prior to implantation: in vitro comparison between daptomycin, rifampin and nebacetin. Eur J Vasc Endovasc Surg 2012;43:448.
